The present invention relates to an auxiliary power unit for an aircraft, and particularly relates to an auxiliary power unit utilizing fuel cells for an aircraft.
It is generally known in the art to provide electricity for different functions of an aircraft such as environmental controls or systems and avionics. In addition, other electrical equipment or outlets on the aircraft, such as power outlets for passengers"" use or electrical controls for controlling the aircraft, require electricity. Most often, the electricity for these systems is provided from the engines of the aircraft. The engines of the aircraft power generators which create electricity for use in these and other subsystems on the aircraft.
It is also known to provide an auxiliary power unit to provide electricity for use on an aircraft. The auxiliary power unit (APU) provides electricity in addition to, or supplementary to, the power produced by the engine generators. Generally, the APUs use gas turbine engines, similar to those of the engine, although smaller. An APU turbine is, therefore, limited in efficiency and creates gaseous emissions similar to the engines. The emissions of the APU at the airport are relatively high when compared to the engines. In addition, the APU reduces the overall fuel efficiency of the aircraft by converting jet fuel to electricity through internal combustion. Turbine APUs also reduce fuel efficiency of the aircraft.
Turbine APUs also create high levels of noise exterior to the aircraft. This requires ground crew to use extra hearing protection even when the engines of the aircraft are not running. This is generally because the turbine APUs are run at the airport to power aircraft systems prior to take off.
Therefore, it would be desirable to provide an APU which does not create additional noise and discomfort to the passengers or ground crew. In addition, it is desired to provide an efficient and clean source of electricity. It is also desired to use an APU that provides nearly all of the electricity required on an aircraft. Aircraft engines may be reduced in size and increased in efficiency by removing the need for the engines to provide compressed air and electricity to the aircraft.
The present invention relates to an auxiliary power unit (APU) for an aircraft. The auxiliary power unit, utilizing solid oxide fuel cells, creates electricity through the migration of oxygen ions. In particular, the solid oxide electrolytes of the fuel cells provide for reformed fuel to cause oxygen migration across the electrolyte. The auxiliary power unit, utilizing solid oxide fuel cells, can power systems of the aircraft and produce water for use in the aircraft. Furthermore, the auxiliary power unit can provide all of the electricity to the aircraft allowing for more efficient aircraft engine design and a decrease in aircraft engine size.
A first preferred embodiment of the present invention provides an aircraft comprising a fuselage, wherein the fuselage comprises a cabin defining a volume of air including oxygen, and an engine for powering the aircraft in flight. A fuel supply provides fuel to the engine. Electronic components are arranged in the aircraft to control a plurality of functions of the aircraft. A power unit, comprising a fuel cell, including a solid electrolyte provides a first source of electricity for the electronic components. The fuel supply supplies the fuel to the power unit so that the power unit produces electricity.
A second preferred embodiment of the present invention provides an auxiliary power unit for an aircraft. The auxiliary power unit comprises a solid oxide fuel cell including a solid oxide electrolyte. A fuel supply supplies fuel to the auxiliary power unit. A fuel reformer reforms the fuel from the fuel supply to constituent elements comprising carbon monoxide and molecular hydrogen for use in the solid oxide fuel cell. An air supply system provides an oxidizer, wherein oxidizer is oxygen to the solid oxide fuel cell. A turbine powered by the solid oxide fuel cell is adapted to provide power to the oxygen supply system. The solid oxide fuel cell is adapted to allow the transport of oxygen ions from the oxygen supply system to combine with the reformed fuel to produce electricity.
The present invention also provides for a method of providing power to an aircraft. The method involves providing a solid oxide fuel cell comprising a solid oxide electrolyte, providing a fuel to the solid oxide fuel cell, and providing an oxidizer to the solid oxide fuel cell. Electricity is produced by passing the oxidizer through the solid oxide electrolyte. The method also involves powering a reclamation system with thermal energy from the solid oxide fuel cell to provide the oxidizer to the solid oxide fuel cell.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.